Flexible organic electroluminescent device and method for fabricating the same

ABSTRACT

Provided is a flexible organic electroluminescent device and a method for fabricating the same. In the flexible electroluminescent device, line hole patterns are formed on surfaces of a plurality of inorganic layers positioned in a pad region in which a flexible printed circuit board is connected to prevent a path of cracks caused by repeated bending and spreading of the organic electroluminescent device from spreading to the interior of the device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of the Korean Patent Application No.10-2013-0104342 filed on Aug. 30, 2013, and Korean Patent ApplicationNo. 10-2013-0149446, filed on Dec. 3, 2013, which are herebyincorporated by reference for all purposes as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an organic electroluminescent device(or an organic light emitting display device. More particularly, thepresent invention relates to a flexible organic electroluminescentdevice capable of minimizing the generation of cracks by a step portionwith a line hole formed in a pad region in which cracks are readilygenerated, or a non-display region including the pad region, and amethod for fabricating the same.

2. Discussion of the Related Art

An organic electroluminescent device, one of flat panel displays (FPDs),has a high degree of luminance and low operational voltagecharacteristics. Also, because the organic electroluminescent device isa self-luminous device, it has a large contrast ratio, is able to beused as an ultra-thin display, has a response time as fast as a fewmicroseconds (μs) to facilitate implementation of a video, has nolimitation in a viewing angle, is stable at low temperatures, and isdriven at a low voltage ranging from 5V to 15V of direct current.

Also, the fabrication process of the organic electroluminescent devicerequires only deposition and encapsulation equipment, which is thus verysimple.

The organic electroluminescent device having the foregoingcharacteristics is divided into a passive matrix type organicelectroluminescent device and an active matrix type organicelectroluminescent device. In the passive matrix type organicelectroluminescent device, scan lines and signal lines cross in a matrixform, and in order to drive each pixel, the scan lines are sequentiallydriven over time. Thus, in order to obtain the required averageluminance, instantaneous luminance corresponding to a value obtained bymultiplying the number of lines to average luminance (i.e.,instantaneous luminance as high as the product of average luminance andthe amount of lines) is required to be obtained.

However, in the active matrix type organic electroluminescent device, athin film transistor (TFTs) is used as a switching element for turningon or off a pixel region and positioned in each pixel region. The TFT isconnected to a power line and an organic light emitting diode (OLED) ineach pixel region.

In this case, a first electrode connected to the driving TFT is turnedon and off by pixel region, and a second electrode facing the firstelectrode may serve as a common electrode. The first electrode and thesecond electrode form the OLED together with an organic light emittinglayer interposed therebetween.

In the active matrix type organic electroluminescent device having theforegoing characteristics, a voltage applied to the pixel region ischarged in a storage capacitor Cst to supply power until when a nextframe signal is applied, whereby the device is continuously drivenduring a single screen regardless of an amount of scan lines.

Thus, although a low current is applied, the same luminance can beobtained, having advantages in that less power is consumed, a fine pitchcan be obtained, and a display size can be increased. These featureshave led to an increase in active matrix type organic electroluminescentdevices being commonly used.

The related art organic electroluminescent device will be described withreference to FIGS. 1 and 2.

FIG. 1 is a plan view illustrating the related art organicelectroluminescent display device.

FIG. 2 is a cross-sectional view of the related art organicelectroluminescent device taken along line II-Ii in FIG. 1.

In FIG. 1, the related art organic electroluminescent device 10, adisplay region AA is defined in a substrate (not shown), a non-displayregion (not shown) having a pad region PD is defined in an outer side ofthe display region AA, a plurality of pixel regions (not shown) definedas regions captured by the gate lines (not shown) and data lines (notshown) are provided in the display region AA, and power lines (notshown) are provided in parallel to the data lines (not shown).

A TFT is formed in each pixel region (not shown).

In the related art organic electroluminescent device 10, a substrate (11in FIG. 2) in which the TFT and an organic electroluminescent element(or an OLED) E are formed is encapsulated with a protective film (47 inFIG. 2).

In detail, as illustrated in FIG. 2, the display region AA is defined inthe substrate 11, and a non-display region including a pad region PD isdefined in an outer side of the display region AA. A plurality of pixelregions (not shown) defined by regions formed by the gate lines (notshown) and the data lines (not shown) are provided in the display regionAA, and power lines (not shown) are provided in parallel to the datalines (not shown).

Here, a polyimide layer 15 is formed on the substrate 11 made of a glassmaterial, and a sacrificial layer 13 is formed between the polyimidelayer 15 and the substrate 11.

A buffer layer 17 made of an insulating material, e.g., silicon oxide(SiO₂) or silicon nitride (SiNx) as an inorganic insulating material, isformed on the polyimide layer 15.

Also, an active layer 19 is formed in each pixel region of the displayregion AA above the buffer layer (not shown). The active layer 19includes a channel region 19 a made of pure polysilicon and having acentral portion forming a channel, and a source region 19 b and a drainregion 19 c formed on both sides of the channel region 19 a and havingimpurities doped with high concentration.

A gate insulating layer 21 is formed on the buffer layer (not shown)including the active layer 19, and a gate electrode 23 is formed tocorrespond to the channel region 19 a of each active layer 19 above thegate insulating layer 21.

Also, a gate line (not shown) is formed to extend from the gateelectrode 23 in one direction above the gate insulating layer 21.

An interlayer insulating layer 25 is formed on the entire surface of thedisplay region above the gate electrode 23 and the gate line (notshown). In this case, the interlayer insulating layer 25 and theunderlying gate insulating layer 21 include contact holes (not shown)exposing the source region 19 a and the drain region 19 c positioned onboth sides of the channel region 19 a of each active layer,respectively.

Also, a data line (not shown) is formed above the interlayer insulatinglayer 25 including the contact holes (not shown). The data line crossesa gate line (not shown) to define a pixel region, and is made of ametal. A power line (not shown) is formed to be spaced apart from thedata line. Here, the power line (not shown) may also be formed to bespaced apart from the gate line and parallel to the gate line (notshown) on the layer in which the gate line (not shown) is formed,namely, on the gate insulating layer.

A source electrode 27 a and a drain electrode 27 b are formed on theinterlayer insulating layer 25. The source electrode 27 a and the drainelectrode 27 b are spaced apart from each other, are in contact with thesource region 19 b and the drain region 19 c , respectively, exposedthrough the contact holes (not shown), and are made of the same metal asthat of the data line (not shown). In this case, the active layer 19,the gate insulating layer 21, the gate electrode 23, and the interlayerinsulating layer 25, which are sequentially stacked, and the sourceelectrode 27 a and the drain electrode 27 b formed to be spaced apartfrom each other all form a TFT (T).

A first passivation layer 31 having a drain contact hole exposing thedrain electrode 27 b of the TFT (T) and a planarization layer 33 isformed on the TFT.

Also, a first electrode 35 is formed on the planarization layer 33. Thefirst electrode 35 is in contact with the drain electrode 27 b of theTFT (T) through the drain contact hole and is separated by pixel region.

A pixel defining layer 37 is formed on the first electrode 35 toseparately form each pixel region. In this case, the pixel defininglayer 37 is disposed between adjacent pixel regions.

An organic light emitting layer 39 is formed on the first electrodewithin each pixel region surrounded by the pixel defining layer 37 andincludes light emitting layers (not shown) emitting red, green, and bluelight.

Also, a second electrode 41 is formed on substantially the entiresurface of the display region AA including on the organic light emittinglayer 39 and the pixel defining layer 37. In this case, the firstelectrode 35, the second electrode 41, and the organic light emittinglayer 39 interposed between the two electrodes 35 and 41 form an organicelectroluminescent element E.

An organic layer 43 is formed on the entire surface of the substrateincluding the second electrode 41, and a second passivation layer 45 isformed on the organic layer 43.

A barrier film 47 is positioned on the second passivation layer 45 inorder to encapsulate the organic electroluminescent element E andprevent moisture transmission. A press sensitive adhesive (PSA) (notshown) is interposed to be completely and tightly attached to thesubstrate 11 and the barrier film 47 without an air layer. Apolarization plate 53 is disposed on the barrier film 47. In this case,the second passivation layer 45, the PSA, and the barrier film 47 form aface seal structure.

In this manner, the substrate 11 and the barrier film 47 are fixed bythe PSA to form a panel state, constructing the related art organicelectroluminescent device.

In order to make the organic electroluminescent device 10 configured asdescribed above into a flexible organic electroluminescent device,first, a rear surface of the substrate 11 of the organicelectroluminescent device 10 is cleaned, and laser is irradiated toseparate the sacrificial layer 13 interposed between the substrate 11and the polyimide layer 15, thus delaminating the substrate 11 from theorganic electroluminescent device 10.

Thereafter, a back plate is laminated on a surface of the polyimidelayer 15 of the separated organic electroluminescent device to form aflexible organic electroluminescent device.

However, when the substrate 11 is separated from the organicelectroluminescent device to fabricate the flexible organicelectroluminescent device, the organic electroluminescent device 10 isbent due to self-stress of the barrier film 47, the polarization plate53, and the TFT (T) constituting the organic electroluminescent device.

FIG. 3 is a schematic perspective view of the related art organicelectroluminescent device illustrating a scenario in which cracks arespread from the pad region of the organic electroluminescent device tocause a curling phenomenon in the organic electroluminescent device.

As illustrated in FIG. 3, during the process of laminating a back plate(not shown) on the surface of the polyimide layer 15 without thesubstrate 11, bending and spreading are repeated to generate cracks C ina vulnerable region, e.g., the pad region PD to which a flexible printedcircuit board (FPCB) is connected, and the cracks C spread even to theTFT part to result in a defective organic electroluminescent device. Inparticular, after the substrate 11 is removed, the layers constitutingthe pad region PD are mostly inorganic layers, and the polyimide layer15 is so brittle as to be vulnerable to a generation of cracks. Thus, infabricating the related art flexible organic electroluminescent device,because cracks C are generated in the pad region PD to which the FPCB isconnected, i.e., a weak region, due to the repetition of bending andspreading to the TFT within the device, to produce a defective organicelectroluminescent device.

Also, the cracks increase during a follow-up process to interfere with asignal line of a panel, which leads to defective driving and a defectivescreen.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a flexible organicelectroluminescent device and method for fabricating the same thatsubstantially obviate one or more problems due to limitations anddisadvantages of the related art.

An advantage of invention is to provide a flexible organicelectroluminescent device in which line hole patterns are formed onsurfaces of a plurality of inorganic layers positioned in a pad regionto which a FPCB is connected, that is weak due to repeated bending andspreading when the organic electroluminescent device is fabricated, inorder to redirect a path of cracks so that the cracks do not spread tothe interior of the device. Thus, damage to the flexible organicelectroluminescent device is minimized.

To achieve these and other advantages and in accordance with the purposeof this specification, as embodied and broadly described herein, aflexible organic electroluminescent device includes: a substrate havinga display region including a plurality of pixel regions and anon-display region including a pad region outside the display region; aplurality of thin film transistors (TFTs) formed in the respective pixelregions on the substrate; an interlayer insulating layer and apassivation layer formed in the display region including the TFTs andthe non-display region in the pad region of the non-display region; atleast one line hole pattern formed in at least one of the interlayerinsulating layer and the passivation layer located at the non-displayregion; a first electrode formed in each pixel region on theplanarization layer and connected to a drain electrode of each TFT; apixel defining layer formed around each pixel region of the substrateincluding the first electrode and the non-display region; an organiclight emitting layer formed separately in each pixel region on the firstelectrode; and a second electrode formed on the entire surface of thedisplay region above the organic light emitting layer.

To achieve these and other advantages and in accordance with the purposeof this specification, as embodied and broadly described herein, amethod for fabricating a flexible organic electroluminescent device,includes: providing a substrate in which a display region including aplurality of pixel regions and a non-display region including a padregion outside the display region are defined; forming a plurality ofthin film transistors (TFTs) in the respective pixel regions on thesubstrate; forming an interlayer insulating layer and a passivationlayer on the entire surface of the substrate including the TFTs; formingat least one line hole pattern in at least one of the interlayerinsulating layer and the passivation layer located at the non-displayregion; forming a planarization layer on the passivation layer; forminga first electrode connected to a drain electrode of each TFT in eachpixel region on the planarization layer; forming a pixel defining layeraround each pixel region of the substrate including the first electrode;forming an organic light emitting layer in each pixel region above thefirst electrode; and forming a second electrode on the entire surface ofthe display region including the organic light emitting layer.

According to the flexible organic electroluminescent device and themethod for fabricating the same according to the present embodiments,line hole patterns are formed in surfaces of a plurality of inorganiclayers, i.e., the gate insulating layer, the interlayer insulatinglayer, and the passivation layer, positioned in a weak region, i.e., apad region to which an FPCB is connected, or a non-display regionincluding the pad region due to repeated bending and in spreading whenthe organic electroluminescent device is fabricated. Thus, a path ofcracks is redirected and prevented from spreading to the interior of thedevice, which minimizes damage to the flexible organicelectroluminescent device.

In particular, because a plurality of line hole patterns are formed in aweak point that is adjacent to a scribe line to redirect a path of linedamage and cracks in the weak point, panel line cracks, as a criticalpoint, can be prevented.

Further, a trimming cutting is applied on trimming lines defined atedges of upper and lower of the pad region of a panel in fabricating ofthe flexible organic electroluminescent device because a curve holepattern is formed at the upper and lower of the pad region to surroundthe trimming line of the pad region so that a path of cracks isredirected and prevented from spreading to the interior of the device;thereby minimizing damage to the flexible organic electroluminescentdevice.

Further, in a case that a trimming cutting is applied on trimming linesdefined at edges of upper and lower of the non-display region locatedopposite to the pad region including the edges of the upper and lower ofthe pad region in fabricating of the flexible organic electroluminescentdevice, because a line hole pattern extended from the curve hole patternis further formed at the non-display region including the pad region tobe surround the trimming line and the display region, so that a path ofcracks is redirected and prevented from spreading to the interior of thedevice; thereby minimizing damage to the flexible organicelectroluminescent device.

Further scope of applicability of the present application will becomemore apparent from the detailed description given hereinafter. However,it should be understood that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from the detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate exemplary embodiments andtogether with the description serve to explain the principles of theinvention.

In the drawings:

FIG. 1 is a plan view illustrating an organic electroluminescent deviceaccording to the related art.

FIG. 2 is a cross-sectional view of the related art organicelectroluminescent device, taken along line II-II in FIG. 1.

FIG. 3 is a schematic perspective view of the related art organicelectroluminescent device, illustrating cracks are transmitted from apad region of the organic electroluminescent device to cause curling ofthe organic electroluminescent device.

FIG. 4 is a plan view illustrating a flexible organic electroluminescentdevice according to an embodiment of the present invention;

FIG. 5 is a schematic cross-sectional view of the flexible organicelectroluminescent device according to an embodiment of the presentinvention, taken along line V-V in FIG. 4.

FIG. 6 is an enlarged cross-sectional view of a pad region of theflexible organic electroluminescent device according to an embodiment ofthe present invention.

FIGS. 7A to 7S are cross-sectional views illustrating a process offabricating the flexible organic electroluminescent device according toan embodiment of the present invention.

FIG. 8 is a schematic perspective view of the flexible organicelectroluminescent device according to an embodiment of the presentinvention.

FIG. 9 is an enlarged plan view of a pad region of the flexible organicelectroluminescent device according to an embodiment of the presentinvention, illustrating a state in which a path of cracks is bypassedalong a plurality of line hole patterns.

FIG. 10 is a perspective view illustrating another example of line holepatterns of the pad region of the flexible organic electroluminescentdevice according to an embodiment of the present invention.

FIG. 11 is a perspective view illustrating another example of line holepatterns of the pad region of the flexible organic electroluminescentdevice according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

A flexible organic electroluminescent device according to embodiments ofthe present invention will be described in detail with reference to theaccompanying drawings.

Hereinafter, embodiments will be described in detail with reference tothe accompanying drawings such that they can be easily practiced bythose skilled in the art to which the present invention pertains. Indescribing the present invention, if a detailed explanation for arelated known function or construction is considered to unnecessarilydivert the gist of the present invention, such explanation will beomitted but would be understood by those skilled in the art. Also,similar reference numerals are used for the similar parts throughout thespecification.

The flexible organic electroluminescent device according to anembodiment of the present invention may be divided into a top emissiontype device and a bottom emission type device based upon a direction inwhich emitted light is transmitted. Hereinafter, the bottom emissiontype device will be described as an example.

The flexible organic electroluminescent device according to anembodiment of the present invention will be described in detail withreference to the accompanying drawings.

FIG. 4 is a plan view schematically illustrating the flexible organicelectroluminescent device according to an embodiment of the presentinvention;

FIG. 5 is a cross-sectional view of the flexible organicelectroluminescent device according to an embodiment of the presentinvention, taken along line V-V in FIG. 4.

FIG. 6 is an enlarged cross-sectional view of a pad region PD of theflexible organic electroluminescent device according to an embodiment ofthe present invention.

Here, a thin film transistor (T) assumes the same as a driving thin filmtransistor (T) as shown in FIG. 5. Further, the thin film transistor (T)can be used as a switching thin film transistor.

In the flexible organic electroluminescent device 100 according to anembodiment of the present invention, a substrate 101 in which a thinfilm transistor (TFT) (not shown) and an organic electroluminescentelement E are formed is encapsulated by a barrier film 151.

In detail, referring to FIGS. 4 and 5, in the flexible organicelectroluminescent device 100 according to an embodiment of the presentinvention, a display region AA is defined on a substrate 101 made of,for example, glass, a non-display region NA having a pad region PD isdefined in an outer side of the display region AA, a plurality of pixelregions (not shown) defined as regions formed by crossings of the gatelines (not shown) and data lines (not shown) are provided in the displayregion AA, and power lines (not shown) are provided in parallel to thedata lines (not shown).

Here, the substrate 101 made of, for example, glass is delaminated afterfabrication of the organic electroluminescent device, and a flexibleback plate (not shown) (161 in FIG. 7S) is laminated on the delaminatedportion. The back plate 161 is formed of a flexible glass substrate or aflexible material, for example a polyimide film, having flexibility sothat although the flexible organic electroluminescent device is bent (orwarped) like paper, for example, the device may still perform as adisplay.

Also, a polyimide layer 105 is formed on the substrate 101, and a bufferlayer 107 having, for example, a multilayer structure made of aninorganic insulating material, e.g., silicon oxide (SiO₂) or a siliconnitride (SiNx) is formed on the polyimide layer 105. In this embodiment,the reason for forming the buffer layer 107 below an active layer 109formed in a follow-up process is to prevent degradation of thecharacteristics of the active layer 109 due to emission of alkali ionsfrom the interior of the substrate 101 when the active layer 109 iscrystallized.

A sacrificial layer 103 made of amorphous silicon or silicon nitride(SiNx) is formed between the substrate 101 and the polyimide layer 105.The sacrificial layer 103 serves to allow the substrate 101 to be easilydelaminated and separated from the polyimide layer 105 through a laserirradiation process after fabrication of the organic electroluminescentdevice.

Also, the active layer 109 is formed in each pixel region of the displayregion AA above the buffer layer 107. The active layer 109 includes achannel region 109 a made of pure polysilicon and having a centralportion forming a channel, and a source region 109 b and a drain region109 c formed in both sides of the channel region 109 a and havingimpurities doped with high concentration.

A gate insulating layer 113 is formed on the buffer layer 107 includingthe active layer 109, and a gate electrode 115 a is formed to correspondto the channel region 109 a of each active layer 109 above the gateinsulating layer 113. At least one line hole pattern 125 c may be formedin a longer-side direction of the pad region PD, namely, opposing thedisplay region AA in an interlayer insulating layer 121 positioned inthe pad region PD.

Also, a gate line (not shown) is formed to extend from the gateelectrode 115 a in one direction above the gate insulating layer 113.The gate electrode 115 a and the gate line (not shown) may be made of afirst metal material, e.g., any one of aluminum (Al), an Al alloy(AlNd), copper (Cu), a Cu alloy, molybdenum (Mo), and molytitanium(MoTi) to have a unilayer structure, or may be formed of two or morefirst metal materials to have a dual-layer or a triple-layer structure.In the drawings, the gate electrode 115 a and the gate line (not shown)are illustrated to have a unilayer structure.

An interlayer insulating layer 121 is formed on the entire surface ofthe display region of the substrate including the gate electrode 115 aand the gate line (not shown). The interlayer insulating layer 121 ismade of an insulating material, e.g., a silicon oxide (SiO₂) or asilicon nitride (SiNx) as an inorganic insulating material. In thiscase, the interlayer insulating layer 121 and the underlying gateinsulating layer 113 include active layer contact holes (not shown)exposing the source region 109 a and the drain region 109 c positionedin both sides of the channel region 109 a of the active layer 109,respectively.

Also, the interlayer insulating layer 121 positioned in the pad regionPD has at least one first line hole pattern 125 c formed therein. Here,the first line hole pattern 125 c is formed in a longer-side directionof the pad region PD, namely, opposing the display region AA.

In addition, a data line (not shown) is formed above the interlayerinsulating layer 121 including the active layer contact holes (notshown). The data line crosses a gate line (not shown) to define a pixelregion (not shown). The data line may be made of a second metalmaterial, e.g., any one or two or more of aluminum (Al), an Al alloy(AlNd), copper (Cu), a Cu alloy, molybdenum (Mo), molytitanium (MoTi),chromium (Cr), and titanium (Ti). A power line (not shown) is formed tobe spaced apart from the data line. In this case, the power line (notshown) may also be formed on a layer in which the gate line is formed,namely, on the gate insulating layer 113 such that it is spaced apartfrom the gate line.

A source electrode 127 a and a drain electrode 127 b are formed on theinterlayer insulating layer 121. The source electrode 127 a and thedrain electrode 127 b are spaced apart from each other, are in contactwith the source region 109 b and the drain region 109 c exposed throughthe active layer contact holes, respectively, and are made of the samesecond metal material as that of the data line (not shown). In thisembodiment, the active layer 109, the gate insulating layer 113, thegate electrode 115 a, and the interlayer insulating layer 121, which aresequentially stacked, and the source electrode 127 a and the drainelectrode 127 b formed to be spaced apart from each other form a TFT(T).

In the drawings, the data line (not shown), the source electrode 127 a,and the drain electrode 127 b are all illustrated to have a unilayerstructure, but these may also have a dual-layer or triple-layerstructure.

Although not shown, a TFT is formed in the switching region (not shown).The switching TFT (not shown) is electrically connected to the drivingTFT, the gate line (not shown), and the data line (not shown). Namely,the gate line (not shown) and the data line (not shown) are connected toa gate electrode (not shown) and a source electrode (not shown) of theswitching TFT (not shown) and a drain electrode (not shown) of theswitching TFT (not shown) is electrically connected to the gateelectrode of the driving TFT (T).

Meanwhile, in the organic electroluminescent device according to anembodiment of the present invention, for example, the driving TFT (T)and the switching TFT (not shown) have the active layer 109 ofpolysilicon and are configured as a top gate type, but the driving TFT(T) and the switching TFT (not shown) may also be configured as a bottomgate type having an active layer of amorphous silicon.

When the driving TFT (T) and the switching TFT (not shown) areconfigured as a bottom gate type, a stacking structure thereof includesa gate electrode, a gate insulating layer, an active layer formed of anohmic-contact layer of impurity amorphous silicon and spaced apart froman active layer of pure amorphous silicon, and a source electrode and adrain electrode spaced apart from each other. In this case, the gateline is formed to be connected to the gate electrode of the switchingTFT in a layer on which the gate electrode is formed, and the data lineis formed to be connected to the source electrode in a layer on whichthe source electrode of the switching TFT is formed.

Meanwhile, a passivation layer 131 and a planarization layer 133,exposing the drain electrode 127 b of the driving TFT (T), are stackedon the driving TFT (T) and the switching TFT (not shown). In this case,an insulating material, e.g., silicon oxide (SiO₂) or a silicon nitride(SiNx) as an inorganic insulating material, is used as a material of theinterlayer insulating layer 121. Also, an organic material includingphoto acryl may be used to form the planarization layer 133.

Meanwhile, at least one second line hole pattern 135 b is formed in aportion of the passivation layer 131 positioned in the pad region PD. Inthis case, the second line hole pattern 135 b is formed in a longer-sidedirection of the pad region PD, namely, opposing the display region AA.The at least one second line hole pattern 135 b may be formed such thatit overlaps with the underlying first line hole pattern 125 c or may notoverlap therewith.

Also, a first electrode 137 is formed on the planarization layer 133.The first electrode 137 is in contact with the drain electrode 127 b ofthe driving TFT (T) through the drain contact hole (not shown), andseparated by each pixel region. The first electrode 137 may be providedas a transparent electrode or a reflective electrode. When the firstelectrode 137 is used as a transparent electrode, it may be made of ITO,IZO, ZnO, or In₂O₃, and when the first electrode 137 is used as areflective electrode, a reflective layer may be formed with Ag, Mg, Al,Pt, Pd, Au, Ni, Nd, Ir, Cr, a compound thereof, and the like, and ITO,IZO, ZnO, or In₂O₃ may be formed thereon.

A pixel defining layer 139 made of an insulating material, inparticular, for example, BCB, polyimide, or photo acryl is formed in aboundary area of each pixel region above the first electrode 137. Inthis case, the pixel defining layer 139 surrounds each pixel region (notshown) and overlaps with edges of the first electrode 137 and has a gridform having a plurality of openings overall in the display region AA.

An organic light emitting layer 141 made of organic materials emittingred, green, and blue light is formed on the first electrode 137 in eachpixel region surrounded by the pixel defining layer 319. The organiclight emitting layer 141 may be configured as a uni-layer made oforganic light emitting materials. Also, although not shown, the organiclight emitting layer 141 may be configured as multiple layers includinga hole injection layer, a hole transporting layer, an emitting materiallayer, an electron transporting layer, and an electron injection layer,in order to enhance luminance efficiency.

Also, a second electrode 143 is formed on substantially an entiresurface of the display region AA including on the organic light emittinglayer 141 and the pixel defining layer 139. In this embodiment, thefirst electrode 137, the second electrode 143, and the organic lightemitting layer 141 interposed between the two electrodes 137 and 143constitute an organic electroluminescence element E.

Thus, when a predetermined voltage is applied to the first electrode 137and the second electrode 143 of the organic electroluminescence elementE according to a selected color signal, holes injected from the firstelectrode 137 and electrons provided from the second electrode 143 aretransported to the organic light emitting layer 141 to form exciton, andwhen the exciton transitions from an excited state to a ground state,light is generated and emitted in the form of visible light. In thiscase, the emitted light is released to the outside through thetransparent second electrode 143, whereby the flexible organicelectroluminescent device implements a certain image.

Meanwhile, a lower passivation layer 145 made of an insulating layer, inparticular, silicon oxide (SiO₂) or a silicon nitride (SiNx) as aninorganic insulating material, is formed on the entire surface of thesubstrate including the second electrode 143. In this case, moistureinfiltration into the organic light emitting layer 141 cannot becompletely prevented only by the second electrode 143, so the lowerpassivation layer 145 is formed on the second electrode 143, thuscompletely preventing moisture infiltration into the organic lightemitting layer 141.

Also, an organic layer 147 made of a polymer organic material such aspolymer is formed on the lower passivation layer 145 in the displayregion AA. In this case, as the polymer used to form the organic layer147, an olefin-based polymer (polyethylene or polypropylene),polyethyleneterephthalate (PET), an epoxy resin, a fluoro resin,polysiloxane, or the like, may be used.

In order to prevent moisture infiltration through the organic layer 147,an upper passivation layer 149 made of an insulating layer, e.g.,silicon oxide (SiO₂) or a silicon nitride (SiNx) as an inorganicinsulating material, is additionally formed on the entire surface of thesubstrate including the organic layer 147.

A barrier film 151 is positioned on the entire surface of the substrateincluding the upper passivation layer 149 in order to encapsulate theorganic electroluminescence element E. Between the substrate 101 and thebarrier film 151, an adhesive (not shown) made of any one among fritwhich is transparent and has bonding characteristics, an organicinsulating material, and a polymer material is interposed to allow thesubstrate 101 and the barrier film 151 to be completely and tightlyattached without an air layer. A polarization plate 153 is disposed onthe barrier film 151.

As the substrate 101 and the barrier film 151 are fixed by the adhesive(not shown) to form a panel state, the organic electroluminescent deviceaccording to an embodiment of the present invention is completed.

Also, in order to make the organic electroluminescent device configuredas described into a flexible organic electroluminescent device, first arear surface of the substrate 101 of the organic electroluminescentdevice is cleaned, and a laser is irradiated to separate the sacrificiallayer 103 interposed between the substrate 101 and the polyimide layer105. Thus, the substrate 101 is delaminated from the organicelectroluminescent device.

Thereafter, a back plate is laminated on a surface of the polyimidelayer 105 of the separated organic electroluminescent device to form aflexible organic electroluminescent device.

In this manner, according to the flexible organic electroluminescentdevice according to an embodiment of the present invention, since theline hole patterns are formed in surfaces of a plurality of inorganiclayers, i.e., the gate insulating layer, the interlayer insulting layer,and the passivation layer, positioned in a pad region (PD), to which anFPCB is connected, which is weak due to repeated bending and spreadingwhen the organic electroluminescent device is fabricated, in order toredirect a path of cracks so as to be prevented from spreading to theinterior of the device, damage to the flexible organicelectroluminescent device can be minimized.

In particular, since a plurality of line hole patterns, for example, 125c and 135 b, are formed in a weak point adjacent to a scribe line SL,when cracks are generated, line damage and a path of cracks in the weakpoint are bypassed, thus preventing panel line cracks, a critical point.

Hereinafter, a method for fabricating a flexible organicelectroluminescent device according to an embodiment of the presentinvention will be described with reference to FIGS. 7A to 7S.

FIGS. 7A to 7S are cross-sectional views illustrating a process offabricating the flexible organic electroluminescent device according toan embodiment of the present invention.

Here, the term film transistor (T) is assumed to be the same as adriving thin film transistor (T) as shown in FIG. 5. Further, the thinfilm transistor (T) can be used as a switching thin film transistor.

As illustrated in FIG. 7A, a substrate 101, for example a glasssubstrate, in which the display region AA and a non-display region (notshown) including the pad region PD outside of the display region AA aredefined is prepared. The substrate 101 is delaminated or removed afterthe fabrication of the organic electroluminescent device, and a flexibleback plate (161 in FIG. 7S) is then laminated on the organicelectroluminescent device. The back plate 161 is formed of a flexibleglass substrate or a material having flexibility so that although theflexible organic electroluminescent device is bent (or warped) likepaper, it may have display performance as is.

Also, a polyimide layer 105 is formed on the substrate 101, and a bufferlayer 107 having a multilayer structure made of an inorganic insulatingmaterial, e.g., silicon oxide (SiO₂) or a silicon nitride (SiNx) isformed on the polyimide layer 105. The reason for forming the bufferlayer 107 below an active layer 109 formed in a follow-up process is toprevent a degradation of the characteristics of the active layer 109 dueto emission of alkali ions from the interior of the substrate 101 whenthe active layer 109 is crystallized.

A sacrificial layer 103 made of amorphous silicon or silicon nitride(SiNx) is formed between the substrate 101 and the polyimide layer 105.The sacrificial layer 103 serves to allow the substrate 101 to be easilydelaminated or separated from the polyimide layer 105 through a laserirradiation process after the fabrication of the organicelectroluminescent device.

As illustrated in FIG. 7B, an active layer 109 is formed in each pixelregion of the display region AA above the buffer layer 107. The activelayer 109 includes a channel region 109 a made of pure polysilicon andhaving a central portion forming a channel, and a source region 109 band a drain region 109 c formed in both sides of the channel region 109a and having impurities doped with high concentration which aredescribed and depicted with respect to FIG. 7F and 7G.

The active layer 109 is formed on the buffer layer 107. In this case,the active layer 109 is made of pure polysilicon in each pixel region ofthe display region AA.

Subsequently, as illustrated in FIG. 7C, a first photosensitive film(not shown) is coated on the active layer 109 and selectively patternedthrough an exposing and developing process to form a firstphotosensitive film pattern 111.

Thereafter, as illustrated in FIG. 7D, the active layer 109 isselectively removed by using the first photosensitive film pattern 111as an etching mask.

Subsequently, as illustrated in FIG. 7E, with the first photosensitivefilm pattern 111 removed, a gate insulating layer 113 and the firstmetal material layer 115 are sequentially deposited on the buffer layer107 including on the active layer 109. In this case, the first metalmaterial layer 115 may be made of a first metal material, e.g., any oneof aluminum (Al), an Al alloy (AlNd), copper (Cu), a Cu alloy,molybdenum (Mo), and molytitanium (MoTi) to have a unilayer structure,or may be formed of two or more first metal materials to have adual-layer or a triple-layer structure. In the drawings, the gateelectrode and the gate line (not shown) are illustrated to have aunilayer structure.

Thereafter, a second photosensitive film (not shown) is coated on thefirst metal material layer 115 and selectively patterned through anexposing and developing process to form a second photosensitive filmpattern 117.

Subsequently, as illustrated in FIG. 7F, the first metal material layer115 is selectively etched by using the second photosensitive filmpattern 117 as an etching mask to form the gate electrode 115 a. A gateline (not shown) is formed to extend from the gate electrode 115 a inone direction above the gate insulating layer 113.

Thereafter, the second photosensitive film pattern 117 is removed, andimpurities are injected into both sides of the active layer 109 belowthe gate electrode 115 a to form the channel region 109 a forming achannel in a central portion of the active layer 109, and the sourceregion 109 b and the drain region 109 c spaced apart from each other onthe basis of the channel region 109 a.

Subsequently, as illustrated in FIG. 7G, the interlayer insulating layer121 made of an insulating material, e.g., a silicon oxide (SiO₂) or asilicon nitride (SiNx) as an inorganic insulating material, is formed onthe entire surface of the display region above the gate electrode 115 aand the gate line (not shown).

Thereafter, a third photosensitive film (not shown) is coated on theinterlayer insulating layer 121 and selectively patterned through anexposing and developing process to form a third photosensitive filmpattern 123.

Subsequently, as illustrated in FIG. 7H, the interlayer insulating layer121 and the underlying gate insulating layer 113 are selectively etchedby using the third photosensitive film pattern 123 as an etching mask tosimultaneously form a source region contact hole 125 a and a drainregion contact hole 125 b exposing the source region 109 b and the drainregion 109 c of the active layer 109. In this case, in forming thesource region contact hole 125 a and the drain region contact hole 125b, at least one first line hole pattern 125 c is also formed in aportion of the interlayer insulating layer 121 positioned in the padregion PD. The first line hole pattern 125 c is formed in thelonger-side direction of the pad region, namely, opposing the displayregion AA.

Thereafter, as illustrated in FIG. 7I, the third photosensitive filmpattern 123 is removed, and a second metal material layer 127 is formedon the interlayer insulating layer 121 including the first line hole 125c. The second metal material layer 127 crosses the gate line (not shown)to define the pixel region (not shown). In this case, the second metalmaterial layer 127 may be made of any one or two or more of aluminum(Al), an Al alloy (AlNd), copper (Cu), a Cu alloy, molybdenum (Mo),molytitanium (MoTi), chromium (Cr), and titanium (Ti).

Subsequently, a fourth photosensitive film (not shown) is coated on thesecond metal material layer 127 and patterned through an exposing anddeveloping process to form a fourth photosensitive film pattern 129.

Thereafter, as illustrated in FIG. 7J, the second metal material layer127 is selectively etched by using the fourth photosensitive filmpattern 129 as an etching mask to form a data line (not shown) crossingthe gate line (not shown) to define the pixel region P and a power line(not shown) spaced apart from the data line. In this case, the powerline (not shown) may be formed on the layer in which the gate line (notshown) is formed, namely, on the gate insulating layer such that it isspaced apart from the gate line (not shown) abreast.

Also, in forming the data line (not shown), the source electrode 127 aand the drain electrode 127 b are formed on the interlayer insulatinglayer 121. The source electrode 127 a and the drain electrode 127 b arespaced apart from each other, are in contact with the source region 109b and the drain region 109 c exposed through the active layer contactholes (not shown), respectively, and are made of the same second metalmaterial as that of the data line (not shown). The active layer 109, thegate insulating layer 113, the gate electrode 115 a, and the interlayerinsulating layer 121, which are sequentially stacked, and the sourceelectrode 127 a and the drain electrode 127 b formed to be spaced apartfrom each other form a TFT (T).

Meanwhile, in the drawings, the data line (not shown), the sourceelectrode 127 a, and the drain electrode 127 b are all illustrated tohave a unilayer structure, but these may also have a dual-layer ortriple-layer structure.

Although not shown, a switching TFT (not shown) having the same stackingstructure as that of the driving TFT (T) is formed. In this case, theswitching TFT (not shown) is electrically connected to the driving TFT,the gate line (not shown), and the data line (not shown). Namely, thegate line (not shown) and the data line (not shown) are connected to agate electrode (not shown) and a source electrode (not shown) of theswitching TFT(not shown) and a drain electrode (not shown) of theswitching TFT (not shown) is electrically connected to the gateelectrode of the driving TFT (T).

Meanwhile, in the organic electroluminescent device according to anembodiment of the present invention, for example, the driving TFT (T)and the switching TFT (not shown) have the active layer 109 ofpolysilicon and are configured as a top gate type, but the driving TFT(T) and the switching TFT (not shown) may also be configured as a bottomgate type having an active layer of amorphous silicon.

When the driving TFT (T) and the switching TFT (not shown) areconfigured as a bottom gate type, a stacking structure thereof includesa gate electrode, a gate insulating layer, an active layer formed of anohmic-contact layer of impurity amorphous silicon and spaced apart froman active layer of pure amorphous silicon, and a source electrode and adrain electrode spaced apart from each other. In this case, the gateline is formed to be connected to the gate electrode of the switchingTFT in a layer on which the gate electrode is formed, and the data lineis formed to be connected to the source electrode in a layer on whichthe source electrode of the switching TFT is formed.

Subsequently, as illustrated in FIG. 7K, with the fourth photosensitivefilm pattern 129 having been removed, a passivation layer 131 is formedon the entire surface of the substrate including the source electrode127 a and the drain electrode 127 b. In this case, as a material of thepassivation layer 131, an insulating material, e.g., a silicon oxide(SiO₂) or a silicon nitride (SiNx) as an inorganic insulating material,is used.

Thereafter, as illustrated in FIG. 7L, the planarization layer 133 madeof an organic material is formed on the passivation layer 131. In thiscase, the organic material may be one selected from the group consistingof polyacryl, polyimide, polyamide (PA), benzocyclobutene (BCB), and aphenol resin, as hydrophobic organic materials having insulatingproperties.

Subsequently, as illustrated in FIG. 7M, the planarization layer 133 andthe underlying passivation layer 131 are sequentially etched to form adrain contact hole 135 a exposing the drain electrode 127 b. In thiscase, in forming the drain contact hole 135 a, at least one second linehole pattern 135 b is also formed in a portion of the passivation layer131 positioned in the pad region PD. Here, the second line hole pattern135 b may be formed in the longer-side direction of the pad region PD,namely, opposing the display region AA and may not overlap with thefirst line hole pattern 125 c formed in the interlayer insulating layer121 or may overlap therewith.

Thereafter, as illustrated in FIG. 7N, a conductive material layer (notshown) is deposited on the planarization layer 133 and selectivelyetched through a masking process to form a first electrode 137 which isin contact with the drain electrode 127 b of the TFT (T) and isseparated by each pixel region. In this case, the conductive materiallayer (not shown) may be provided as a transparent electrode or areflective electrode. When the first electrode 137 is used as atransparent electrode, it may be made of ITO, IZO, ZnO, or In₂O₃, andwhen the first electrode 137 is used as a reflective electrode, areflective layer may be formed with Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir,Cr, a compound thereof, and the like, and ITO, IZO, ZnO, or In₂O₃ may beformed thereon.

Subsequently, as illustrated in FIG. 70, an insulating material layer(not shown) made of, for example, BCB, polyimide, or photo acryl isformed in a boundary area of each pixel region on the first electrode137.

Thereafter, the insulating material layer (not shown) is selectivelypatterned to form the pixel defining layer 139. In this case, the pixeldefining layer 139 is formed to overlap with edges of the firstelectrode 137 such that it surrounds each pixel region, and has a gridform having a plurality of openings overall in the display region AA.

Subsequently, as illustrated in FIG. 7P, the organic light emittinglayer 141 emitting red, green, and blue light is formed on the firstelectrode layer within each pixel region surrounded by the pixeldefining layer 139. In this case, the organic light emitting layer 141may be configured as a uni-layer made of organic light emittingmaterials. Also, although not shown, the organic light emitting layer141 may be configured as multiple layers including a hole injectionlayer, a hole transporting layer, an emitting material layer, anelectron transporting layer, and an electron injection layer, in orderto enhance luminance efficiency.

Thereafter, as illustrated in FIG. 7Q, the second electrode 143 isformed on the entire surface of the display region AA including theorganic light emitting layer 141 and an upper portion and side portionof the pixel defining layer 139. In this case, the second electrode 143may be provided as a transparent electrode or a reflective electrode.When the second electrode 143 is used as a transparent electrode, it isused as a cathode electrode, so a metal having a small work function,i.e., Li, Ca, LiF/Ca, LiF/Al, Al, Ag, Mg, and a compound thereof, isdeposited toward the organic layer 129, on which an auxiliary electrodelayer or a bus electrode line may be formed of a transparent electrodeformation material such as ITO, IZO, ZnO, In₂O₃, or the like. When thesecond electrode 143 is used as a reflective electrode, Li, Ca, LiF/Ca,LiF/Al, Al, Ag, Mg, and a compound thereof is deposited entirely.

Thus, the organic electroluminescence element E, which emits red, green,and blue light according to a flow of a current to display predeterminedimage information, includes the first electrode 137 connected to thedrain electrode 127 b of the TFT (T) to supply positive power therefrom,the second electrode 143 provided to cover the entire pixels to supplynegative power, and the organic light emitting layer 141 disposedbetween the first electrode 137 and the second electrode 143 to emitlight.

The first electrode 137 and the second electrode 143 are insulated fromeach other by the organic light emitting layer 141, and when a voltageis applied, the organic light emitting layer 141 emits light.

Thus, when a predetermined voltage is applied to the first electrode 137and the second electrode 143 of the organic electroluminescence elementE according to a selected color signal, holes injected from the firstelectrode 137 and electrons provided from the second electrode 143 aretransported to the organic light emitting layer 141 to form exciton, andwhen the exciton transitions from an excited state to a ground state,light is generated and emitted in the form of visible light. In thiscase, the emitted light is released to the outside through thetransparent second electrode 143, whereby the flexible organicelectroluminescent device implements a certain image.

Subsequently, as illustrated in FIG. 7R, a lower passivation layer 145made of an insulating layer, in particular, silicon oxide (SiO₂) or asilicon nitride (SiNx) as an inorganic insulating material, is formed onthe entire surface of the substrate including the second electrode 143.In this case, moisture infiltration into the organic light emittinglayer 141 cannot be completely prevented with only the second electrode143. So the lower passivation layer 145 is formed on the secondelectrode 143. Thus, completely preventing moisture infiltration intothe organic light emitting layer 141.

Thereafter, an organic layer 147 made of a polymer organic material suchas polymer is formed in the display region AA and the non-display regionon the lower passivation layer 145 through a method such as screenprinting. In this case, as the polymer used to form the organic layer147, an olefin-based polymer (polyethylene or polypropylene),polyethyleneterephthalate (PET), an epoxy resin, a fluoro resin,polysiloxane, or the like, may be used. The organic layer 147 is formedin the display region AA.

In order to prevent moisture infiltration through the organic layer 147,an upper passivation layer 149 made of an insulating layer, e.g.,silicon oxide (SiO₂) or a silicon nitride (SiNx) as an inorganicinsulating material, is additionally formed on the entire surface of thesubstrate including the organic layer 147.

Thereafter, the barrier film 151 is positioned on the entire surface ofthe substrate including the upper passivation layer 149 in order toencapsulate the organic electroluminescence element E. Between thesubstrate 101 and the barrier film 151, an adhesive (not shown) made ofany one among frit which is transparent and has bonding characteristics,an organic insulating material, and a polymer material is interposed toallow the substrate 101 and the barrier film 151 to be completely andtightly attached without an air layer. Thereafter, a polarization plate153 is attached to the barrier film 151.

As the substrate 101 and the barrier film 151 are fixed by the adhesive(not shown) to form a panel state, the process of fabricating theorganic electroluminescent device according to an embodiment of thepresent invention is completed.

Thereafter, as illustrated in FIG. 7S, in order to make the organicelectroluminescent device configured as described into a flexibleorganic electroluminescent device, first a rear surface of the substrate101 of the organic electroluminescent device is cleaned, and a laser isirradiated to separate the sacrificial layer 103 interposed between thesubstrate 101 and the polyimide layer 105. Thus, delaminating thesubstrate 101 from the organic electroluminescent device.

Thereafter, a back plate 161 is laminated on a surface of the polyimidelayer 105 of the separated organic electroluminescent device, thuscompleting the fabrication process of the flexible organicelectroluminescent device.

FIG. 8 is a schematic perspective view of the flexible organicelectroluminescent device according to an embodiment of the presentinvention.

FIG. 9 is an enlarged plan view of a pad region PD of the flexibleorganic electroluminescent device according to an embodiment of thepresent invention, illustrating a state in which a path of cracks isredirected along a plurality of line hole patterns.

Here, a thin film transistor (T) assumes the same as a driving thin filmtransistor (T) as shown in FIG. 5. Further, the thin film transistor (T)can be used as a switching thin film transistor.

As illustrated in FIG. 8, the line hole patterns 125 c and 135 b areformed in the surfaces of a plurality of inorganic layers, e.g., theinterlayer insulating layer 121 and the passivation layer 131,positioned in the pad region PD, to which an FPCB 170 is connected,which is weak due to repeated bending and spreading when the organicelectroluminescent device is fabricated.

As illustrated in FIG. 9, the line hole patterns 125 c and 135 b areformed to be adjacent to a panel scribe line in the surfaces of theinterlayer insulating layer 121 and the passivation layer 131 positionedin the pad region PD, to which an FPCB 170 is connected, which is weakdue to repeated bending and spreading when the organicelectroluminescent device is fabricated, in order to bypass atransmission path of cracks generated due to absorption and damage tothe weak point in the event of external impact, and thus, transmissionof the cracks to the interior of the display region can be minimized.

Hereinafter, another example of the line hole pattern provided in thepad region of the flexible organic electroluminescent device accordingto an embodiment of the present invention will be described withreference to FIG. 10.

FIG. 10 is a perspective view schematically illustrating another exampleof line hole patterns of the pad region of the flexible organicelectroluminescent device according to an embodiment of the presentinvention.

In the flexible organic electroluminescent device according to anembodiment of the present invention, a separate member, e.g., a cameraor any other members may be disposed as necessary according to anapplication field. In this case, such members may not be disposed in thedisplay region AA, so the pad region PD is used instead.

In this case, since the camera or other components are to be disposed ina portion of the pad region PD, the area of the pad region PD may bereduced as much in designing the pad region.

In this case, since the area of the pad region PD of the flexibleorganic electroluminescent device according to an embodiment of thepresent invention is reduced, the shape of the line hole pattern formedin the pad region PD should be changed.

Here, a case in which first and second line hole patterns 225 and 235according to another embodiment of the present invention are formed onthe gate insulating layer 113, the interlayer insulating layer 121 andthe passivation layer 131 of the first embodiment of the presentinvention illustrated in FIG. 5 will be described as an example.

Namely, a case in which the first line hole pattern 225 is formed in theinterlayer insulating layer 121 and the second line hole pattern 235 isformed on the passivation layer (131 in FIG. 5) will be described as anexample.

Referring to FIG. 10, in the flexible organic luminescent device 200according to an embodiment of the present invention, a display region AAis defined on a substrate (not shown), and a non-display region NAincluding a pad region PD is defined outside the display region AA.

A space portion 240 is provided in both edge portions of the non-displayregion such that it is adjacent to the pad region PD, to allow a cameraor any other members to be disposed therein. The pad region PD has anarea smaller than that of the first embodiment, and thus, the first andsecond line hole patterns 225 and 235 formed in the interlayerinsulating layer (not shown) and the passivation layer (not shown)positioned in the pad region PD have a shape different from thepreviously disclosed shape.

Here, the first and second line hole patterns 225 and 235 include linearportions 225 a and 235 a and bent portions 225 b and 235 b,respectively. The linear portions 225 a and 235 a correspond to centralregions of the first and second line hole patterns 225 and 235, and thebent portions 225 b and 235 b correspond to both side end regions of thefirst and second line hole patterns 225 and 235.

Thus, since the bent portions 225 b and 235 b are formed in both sideend regions of the first and second line hole patterns 225 and 235 inconsideration of the reduction in the area of the pad region PD asnecessary, a path of cracks due to impact, or the like, generated due tothe repeated warping (or bending) or spreading in fabricating theflexible organic luminescent device can be bypassed so as not to betransmitted to the interior of the device, thus minimizing damage to theflexible organic luminescence device.

In this manner, according to the flexible organic luminescent deviceaccording to embodiments of the present invention, line hole patternsare formed in surfaces of a plurality of inorganic layers, i.e., thegate insulating layer, the interlayer insulating layer, and thepassivation layer, positioned in a weak region, i.e., a pad region PD towhich an FPCB is connected, because of repeated bending and spreadingwhen the organic electroluminescent device is fabricated. Thus, a pathof cracks is redirected and prevented from being spread to the interiorof the device, which minimizes damage to the flexible organicelectroluminescent device.

In particular, because a plurality of line hole patterns is formed in aweak point adjacent to a scribe line to redirect a path of line damageand cracks in the weak point, panel line cracks as a critical point canbe prevented.

Another example of the line hole pattern provided in the pad region ofthe flexible organic electroluminescent device according to anembodiment of the present invention will be described with reference toFIG. 11.

FIG. 11 provides a perspective view schematically illustrating anotherexample of line hole patterns of the pad region of the flexible organicelectro luminescent device according to an embodiment of the presentinvention.

In the flexible organic electroluminescent device 300, a display regionAA is defined on a substrate made of, for example, glass, a non-displayregion NA having a pad region PD is defined in an outer side of thedisplay region AA, a plurality of pixel region (not shown) defined asregions formed by crossings of the gate lines (not shown) and data lines(not shown) are provided in the display region AA, and power lines (notshown) are provided in parallel to the data lines (not shown).

A scribe line SL is defined outside of the non-display region NA, and afirst trimming line TL1 is defined at an edge of upper and lower of thepad region PD, and a second trimming line TL2 is defined at edges ofupper and lower of the non-display region located opposite to the padregion.

In fabrication of the flexible organic electroluminescent device, atrimming cutting is applied on the first and second trimming lines TL1and TL2.

As shown in FIG. 11, a first hole pattern 325 a surrounding the firsttrimming line is formed at edges of upper and lower of the pad regionPD. The first hole pattern 325 a may be formed to have a curve type orlinear type. Accordingly, due to the first hole pattern 325 a, a path ofcracks is redirected and prevented from spreading to the interior of thedevice; thereby minimizing damage to the flexible organicelectroluminescent device.

Further, as illustrated in FIG. 11, a second hole pattern 325 b extendedfrom the first hole pattern 325 a is formed at the non-display region NAlocated at outside of the display region AA opposite to the pad regionPD. A crack preventing hole pattern 325 comprised the first hole pattern325 a and the second hole pattern 325 b.

Accordingly, because all of the crack preventing hole 325 is formed bythe first hole pattern 325 a and the second hole pattern 325 b, a pathof cracks is redirected and prevented from spreading to the interior ofthe device. For example, a crack spreading from the second trimming lineto the interior of the display region AA, and a crack spreading from thefirst trimming line of the pad region to the interior of the displayregion AA.

As disclosed above, according to the flexible organic electroluminescentdevice and the method for fabricating the same according to the presentembodiments, line hole patterns are formed in surfaces of a plurality ofinorganic layers, i.e., the gate insulating lyer, the interlayerinsulating layer, and the passivation layer, positioned in a weakregion, i.e., a pad region to which an FPCB is connected, or anon-display region including the pad region due to repeated bending andspreading when the organic electroluminescent device is fabricated.Thus, a path of cracks is redirected and prevented from spreading to theinterior of the device which minimizes damage to the flexible organicelectroluminescent device.

In particular, because a plurality of line hole patterns are formed in aweak point that is adjacent to a scribe line to redirect a path of linedamage and cracks in the weak point, panel line cracks, as a criticalpoint, can be prevented.

Further, because a curve hole pattern is formed at the periphery part ofthe trimming line to surrounding the trimming line of the pad region, apath of cracks is redirected and prevented from spreading to theinterior of the device, which minimizes damage to the flexible organicelectroluminescent device.

Meanwhile, because a line hole pattern extended from the curve holepattern is further formed at the non-display region including the padregion surrounding the trimming line and the display region, a path ofcracks is redirected and prevented from spreading to the interior of thedevice, which minimizes damage to the flexible organicelectroluminescent device.

The foregoing embodiments and advantages are merely exemplary and arenot to be considered as limiting the present disclosure. The presentteachings can be readily applied to other types of apparatuses. Thisdescription is intended to be illustrative, and not to limit the scopeof the claims. Many alternatives, modifications, and variations will beapparent to those skilled in the art. The features, structures, methods,and other characteristics of the exemplary embodiments described hereinmay be combined in various ways to obtain additional and/or alternativeexemplary embodiments.

As the present features may be embodied in several forms withoutdeparting from the characteristics thereof, it should also be understoodthat the above-described embodiments are not limited by any of thedetails of the foregoing description, unless otherwise specified, butrather should be considered broadly within its scope as defined in theappended claims, and therefore all changes and modifications that fallwithin the metes and bounds of the claims, or equivalents of such metesand bounds are therefore intended to be embraced by the appended claims.

What is claimed is:
 1. A flexible organic electroluminescent devicecomprising: a substrate having a display region including a plurality ofpixel regions and a non-display region including a pad region outsidethe display region; a plurality of thin film transistors (TFTs) formedin the respective pixel regions on the substrate; an interlayerinsulating layer formed in the display region including the TFTs and thenon-display region, and having at least one first line hole patternformed in the pad region of the non-display region; a passivation layerformed on the interlayer insulating layer; wherein the at least one linehole pattern is formed in at least one of the interlayer insulatinglayer and the passivation layer and located at the non-display region; aplanarization layer formed on the passivation layer; a first electrodeformed in each pixel region on the planarization layer and connected toa drain electrode of each TFT; a pixel defining layer formed around eachpixel region of the substrate including the first electrode and thenon-display region; an organic light emitting layer formed separately ineach pixel region on the first electrode; and a second electrode formedon the entire surface of the display region above the organic lightemitting layer.
 2. The flexible organic electroluminescent device ofclaim 1, further comprising: a lower passivation layer formed on theentire surface of the substrate including the second electrode; anorganic layer formed on the lower passivation layer in the displayregion; an upper passivation layer formed on the first passivation layerincluding the organic layer; a barrier film disposed to face thesubstrate; and a polarization plate attached to the barrier film.
 3. Theflexible organic electroluminescent device of claim 1, wherein thesubstrate is a flexible glass substrate having flexible characteristicsor is made of a flexible material.
 4. The flexible organicelectroluminescent device of claim 1, wherein the line hole patternsoverlap.
 5. The flexible organic electroluminescent device of claim 1,where the line hole patterns do not overlap.
 6. The flexible organicelectroluminescent device of claim 1, wherein the line hole patterns areformed at a pad region of the non-display region or at the non-displayregion including the pad region.
 7. The flexible organicelectroluminescent device of claim 1, wherein at least one line holepattern is also formed in the pad region of the gate insulating layer.8. The flexible organic electroluminescent device of claim 6, whereinthe line hole pattern of a curve type formed at the non-display regionincluding the pad region includes a first hole pattern having curveportions surrounding a trimming line formed at edges of an upper and alower of the pad region, and a second hole pattern extended from thefirst hole pattern having linear portions surrounding the display regionat the non-display region located at an outside of the display regionopposite to the pad region.
 9. The flexible organic electroluminescentdevice of claim 1, wherein a polyimide layer and a plurality of bufferlayers are interposed between the substrate and the plurality of thinfilm transistors.
 10. A method for fabricating a flexible organicelectroluminescent device, the method comprising: providing a substratein which a display region including a plurality of pixel regions and anon-display region including a pad region outside the display region aredefined; forming a plurality of thin film transistors (TFTs) in therespective pixel regions on the substrate; forming an interlayerinsulating layer on the entire surface of the substrate including theTFTs; forming a passivation layer on the interlayer insulating layer;forming at least one line hole pattern in at least one of the interlayerinsulating layer and the passivation layer located at the non-displayregion; forming a planarization layer on the passivation layer; forminga first electrode connected to a drain electrode of each TFT in eachpixel region on the planarization layer; forming a pixel defining layeraround each pixel region of the substrate including the first electrode;forming an organic light emitting layer in each pixel region above thefirst electrode; and forming a second electrode on the entire surface ofthe display region including the organic light emitting layer.
 11. Themethod of claim 10, further comprising: forming a lower passivationlayer on the entire surface of the substrate including the secondelectrode; forming an organic layer on the lower passivation layer inthe display region; forming an upper passivation layer on the firstpassivation layer including the organic layer; forming a polarizationplate together with a barrier film on the upper passivation layer;delaminating the substrate; and laminating a back plate to the portionfrom which the substrate was delaminated, after the forming of thesecond electrode on the entire surface of the display region includingthe organic light emitting layer.
 12. The method of claim 10, whereinthe hole patterns are formed to overlap.
 13. The method of claim 10,wherein the line hole patterns are formed to not overlap.
 14. The methodof claim 10, wherein the line hole patterns are formed at a pad regionof the non-display region or at the non-display region including the padregion.
 15. The method of claim 10, wherein at least one line holepattern is formed in the pad region of the gate insulating layer. 16.The method of claim 14, wherein the line hole pattern formed at thenon-display region including the pad region includes a first holepattern having curved portions surrounding a trimming line formed atedges of an upper and a lower of the pad region, and a second holepattern extended from the first hole pattern having linear portionssurrounding the display region at the non-display region located at anoutside of the display region opposite to the pad region.
 17. The methodof claim 10, wherein a polyimide layer and a plurality of buffer layersare interposed between the substrate and the plurality of thin filmtransistors.